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Ultracold Quantum Gases Group

Welcome to the ultracold quantum gas research group at Aarhus University!

In our research we investigate the properties of atomic gases at extremely low temperatures. This allows us to understand the fundamental quantum mechanical behaviour of these many particle systems.

News

Congratulations to Poul!

On the 7th of November, Poul Lindholm Pedersen successfully defended his PhD thesis "Multi-mode spin dynamics of a Bose-Eintein condensate in an optical lattice". The assessment committee consisted of Chargé de recherché Fabrice Gerbier from Collège de France in Paris and Prof. Dr. Artur Widera from the Kaiserslautern University of Technology. (10/2014)


Left: 39K. Right: 87Rb

First dual condensate in MIX lab

The first heteronuclear 39K-87Rb BEC-Mixtures were produced in the MIX laboratory on the 12th of May. The inter-species tunablility of the scattering length between 39K-87Rb allows for a wide range of exciting experiments including fundamental investigations of interactions in heteronuclear many particle quantum systems, molecular quantum gasses, and the simulation of the impurity problem under changing interactions. Currently, both condensates have around 104 atoms. (05/2014)


Time limited optimal dynamics beyond the Quantum Speed Limit

The quantum speed limit sets the minimum time required to transfer a quantum system completely into a given target state. At shorter times the higher operation speed has to be paid with a loss of fidelity. Here we quantify the trade-off between the fidelity and the duration in a system driven by a time-varying control and interpret the result in Hilbert space geometry. Formulating a necessary convergence criterion for Optimal Control (OC) algorithms allows us to implement an algorithm which minimizes the process duration while obtaining a predefined fidelity. http://arxiv.org/abs/1405.6079 (05/2014)


Spin dynamics in a two dimensional quantum gas

Published in Physical Review A, Rapid comm.!

We have investigated spin dynamics in a 2D quantum gas. Through spin-changing collisions, two clouds with opposite spin orientations are spontaneously created in a Bose-Einstein condensate. After ballistic expansion, both clouds acquire ring-shaped density distributions with superimposed  angular density modulations. The  density distributions depend on the applied magnetic field and are well explained by a simple Bogoliubov model. We  show that the two clouds are anti-correlated in momentum space. The observed momentum correlations pave the way towards the creation of an atom source with non-local Einstein-Podolsky-Rosen entanglement. (05/2014)


One- and two-qubit quantum gates using superimposed optical-lattice potentials

Published in Physical Review A!

We propose an architecture which allows for the merger of a selected qubit pair in a long-periodicity superlattice structure consisting of two optical lattices with close-lying periodicity. We numerically optimize the gate time and fidelity, including the effects on neighboring atoms and in the presence of experimental sources of error. Furthermore, the superlattice architecture induces a differential hyperfine shift, allowing for single-qubit gates. The fastest possible single-qubit gate times, given a maximal tolerable rotation error on the remaining atoms at various values of the lattice wavelengths, are identified. (03/2014)


Funding

Our research is supported by:

The Danish National Research Foundation within the Center for Quantum Optics (QUANTOP).

Henvendelse om denne sides indhold: 
Revideret 10.11.2014

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Kontaktinformation

Institut for Fysik og Astronomi
Aarhus Universitet
Ny Munkegade 120
8000 Aarhus C

E-mail: phys@au.dk
Tlf: 8715 0000 (Aarhus Universitets hovednummer)
Fax: 8612 0740


Medarbejdere, studerende, ledelse

Nyttige numre

CVR-nr: 31119103

Momsnummer/VAT: DK 3111 9103
(alle internationale køb)

P-nr: 1009828059

EAN-nr: 5798000419872

Stedkode: 2902

Enhedsnummer: 5200

Aarhus Universitet
Nordre Ringgade 1
8000 Aarhus C

E-mail: au@au.dk
Tlf: 8715 0000
Fax: 8715 0201

CVR-nr: 31119103
EAN-numre: www.au.dk/eannumre

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